1. Field of the Invention
The present invention relates to a structural graph display system, and more particularly, to a structural graph display system for generating a new structural graph by changing sub-graphs of an existent structural graph.
2. Description of the Prior Art
At present, high quality Chinese characters are commonly formed by using a stroke-combined character technique wherein each Chinese character is considered a structural graph formed by a plurality of strokes, each stroke being a sub-graph formed by its individual contour. Although the varieties of strokes used in forming Chinese characters are few, the length, thickness and orientation of like strokes differ based on their placement within the word. Despite these differences, the contour of any stroke, such as the stroke, {character pullout}, remains relatively constant. Thus, if the length, angle, key point(s) and stroke width(s) of one stroke can be determined separately, the contour of the stroke can be easily drawn by executing a generation program.
Basically, each stroke has a fixed number of key points and stroke widths, and each stroke can be drawn by a stroke generation program. The stroke generation program is written by Graphic description language, and can draw the contour of one stroke in a rectangular area according to each given key point and stroke width. Each character is a combination of individual strokes sequentially drawn in a rectangular area by executing the stroke generation program of each stroke.
Please refer to FIG. 1 FIG. 1 shows a data structure of a prior art stroke table 10. Each stroke on the stroke table 10 has a stroke ID 12 and a stroke generation program 14. The computer system draws the contour of the stroke in a rectangular area using the stroke generation program corresponding to the stroke ID and using the key point(s) and stroke width(s) parameters of the stroke.
Please refer to FIG. 2 and FIG. 3. FIG. 2 shows the contour of a stroke 20 and the position of each key point and stroke width. FIG. 3 shows a data structure 30 of the stroke 20. The stroke 20 has three key points (x1,y1), (x2, y2), (x3, y3) and two stroke widths w1,w2. The data structure 30 comprises a stroke ID (ID 7) of the stroke 20, the key positions and stroke widths.
Please refer to FIG. 4. FIG. 4 shows a data structure of a prior art character description file 40. The character description file 40 is used for storing the strokes contained within the character, and the stroke ID, key point, stroke width of each stroke. The character description file 40 contains an index table 42 and stroke description table 44 of each character. The index table 42 contains a word ID (WID) for each character and the address of the corresponding stroke description table 44. The stroke description table 44 is a combination of the data structures of all strokes of a character. Like the data structure 30 shown in FIG. 3, the stroke description table 44 comprises the stroke data of all strokes: stroke IDs, key points, and stroke widths. The stroke data are arranged in a predetermined order, such as the writing sequence. When drawing a character, the computer system can locate the stroke description table 44 of the character by using the index table 42 of the stroke description table 44 as long as the word ID of the character is known. Afterward, the computer system will draw all strokes of the character one by one in a rectangular area in conjunction with the stroke table 10.
An operational stroke-combined character technique must have good contour information. This includes both an index table to indicate which strokes constitute a character and a stroke description table to indicate key points and stroke width of each stroke. To determine this data, each character must be written on paper and then digitized stroke by stroke so as to analyze parameters of all key points and stroke widths and accordingly build the index table and character description table. Since each character of a new font must be equipped with a stroke table and character description table and a Chinese font commonly contains about fourteen thousand characters, producing a new font may take about half a year to ensure that the stroke-combined character technique is functional. This is a time consuming process and as such there is a dearth of fonts available.